DESCRIPTION: Safe, injectable, elastomeric biomaterials to augment tissue volume and improve biomechanical functions during tissue regeneration remain as a significant clinical need. One example is preterm birth, which occurs in greater than 500,000 pregnancies per year, or 12.3% of all pregnancies in the U.S., and for which there remain poor clinical options. To address this need, in our recent studies we have developed a new family of silk protein-based elastomers with an extraordinary range of mechanical features and based on an FDA approved material. The features of these protein elastomers include tunable mechanics, tunable biodegradation, biocompatibility and options for growth factor decoration, suggesting a suitable match to the needs in the field of soft tissue augmentation. The hypothesis is that modulating silk elastomer formation and functionalization can provide a new family of injectable elastomers to meet a broad range of tissue augmentation needs, such as for the treatment of preterm birth. The planned studies build on our extensive preliminary data, with both fundamental biomaterials studies planned, combined with a targeted clinical application where new options are a current critical need. The goal is to restore cervical tissue functions and prevent preterm birth in instances where dysfunctional cervical tissue is the cause. The three Aims focus on optimizing the biomaterial properties to match mechanics, injectability and kinetics, in vitro assessments of mechanical and biological functions, and in vivo studies of cervical augmentation in a rabbit model.